Mirror adjustment mechanisms are known, for instance, from the Dutch patent publication NL 1015428, where a mirror adjustment mechanism is used to adjust a mirror element in a mirror housing of a motor vehicle. Moreover, the angular position of a mirror element can be varied with respect to a frame that is mounted to the mirror housing, such that a driver of the motor vehicle has an optimum field of vision in rearward direction. Also, mirror adjustment mechanisms can be used to adjust the mirror housing inclusive of the mirror element relative to a base plate that is fixedly mounted on the motor vehicle.
At relatively high speeds of the motor vehicle, or when driving over a road having a rough surface, such as an unimproved road, the mirror element may start to vibrate under the influence of forces exerted by the air flowing past, or as a result of forces transmitted to the mirror housing via the wheels. The cooperating surfaces of the mirror adjustment mechanism then perform vibrations relative to each other. More particularly, the cooperating surfaces alternately move away from and towards each other, or along each other in a direction substantially parallel to one of the cooperating surfaces. Also, a combination of the above-mentioned movements is possible. The vibration of the mirror element adversely affects the driver's view in rearward direction, which is undesired, for instance for reasons of safety.
There are different mechanical constructions known which envisage a vibration-absorbing effect, such as hydraulic or pneumatic shock absorbers and shock damping actuators. Often, however, these are costly, non-compact and less reliable constructions.
An object of the invention is to obtain a mirror adjustment mechanism of the type in which vibrations are prevented. More particularly, an embodiment of the invention contemplates a mirror adjustment mechanism in which vibrations performed by the cooperating surfaces of the mirror adjustment mechanism relative to each other are damped. To that end, a metal salt of a fatty acid may be used.
Surprisingly, it has been found that through the use of such metal salts, the cooperating surfaces of the mirror adjustment mechanism vibrate less at relatively high speeds of the motor vehicle or when driving over a road having a rough surface. The metal salt of a fatty acid, also designated as “fatty acid salt” or “metal soap,” has a lubricating action in low-frequency pivotal motions, while at higher frequencies, a vibration-absorbing action is involved. This effect can be ascribed to the energy absorption that occurs in the metal salt possibly behaving as a fluid. It supposed that upon a high-frequency pivoting of the cooperating surfaces, metal salt particles situated close to one of the surfaces move to a lesser extent relative to that surface than metal salt particles that are further removed from that surface. The friction thereby arising could prevent the unwanted pivotal motion. According to another supporting explanation, the vibration-absorbing effect is obtained in that particles of the metal salt like ball bearings behave as a lubricant at relatively low frequencies, while at relatively high frequencies, by contrast, friction arises between the particles of metal salt and the cooperating surfaces.
Metal soaps are generally known to be applicable as grease, lubricant, anticlotting agent, tabletting aid, hydrophobing agent, separating agent, chemical stabilizer, defoamer and/or detaching agent.
The metal in the metal salt of a fatty acid can be any suitable metal, such as an alkali or alkaline-earth metal, or other metal. Suitable metals are, inter alia, magnesium, calcium, aluminum, zinc, lead, sodium, potassium, barium, lithium, copper, tin, iron, chromium or zirconium. Preferably, the metal is magnesium, calcium, aluminum or zinc, more preferably zinc.
The fatty acid in the metal salt of a fatty acid can be a natural or synthetic fatty acid. Natural fatty acids can be obtained from vegetable or animal sources in manners well known in the art, and such sources include, but are not limited to, vegetable oils, nut oils and seed oils, such as almond oil, castor oil, coconut oil, corn oil, cottonseed oil, jojoba oil, linseed oil, grapeseed oil, rapeseed oil, mustard oil, olive oil, palm oil and palm kernel oil, peanut oil, safflower oil, sesame oil, soybean oil, sunflower oil, crambe oil, wheat germ oil, and cocoa butter; and animal oils and fats, such as lanoline, chicken fat, tallow, lard, beef fat, butterfat, mink oil, and fish oils.
The fatty acids can be fatty acids having a saturated, unsaturated, unbranched or branched chain. Very suitable fatty acids are the following higher fatty acids (C6-C24), specified by the standard chemical name, along with the common name, the number of carbon atoms and the number of double bonds in the fatty acid chain: hexanoic acid (caproic acid; C6:0); heptanoic acid (C7:0); octanoic acid (caprylic acid; C8:0); nonanoic acid (pelargonic acid; C9:0); decanoic acid (capric acid; C10:0); undecanoic acid (C11:0); undecylenic acid (C11:1); dodecanoic acid (lauric acid; C12:0); tridecanoic acid (C13:0); tetradecanoic acid (myristic acid; C14:0); tetradecenoic acid (myristoleic acid; C14:1); pentadecanoic acid (C15:0); pentadecenoic acid (C15:1); hexadecanoic acid (palmitic acid; C16:0); hexadecenoic acid (palmitoleic acid; C16:1); hexadecadienoic acid (C16:2); hexadecatrienoic acid (C16:3); heptadecanoic acid (margaric acid; C17:0); heptadecenoic acid (margaroleic acid; C17:1); octadecanoic acid (stearic acid; C18:0); 9-octadecynoic acid (stearolic acid; C18:1); [Z]-9-octadecenoic acid (oleic acid; C18:1); [E]-9-octadecenoic acid (elaidic acid; C18:1); [R-[Z]]-12-hydroxy-9-octadecenoic acid (ricinoleic acid; C18:1); [Z,Z]-9,12-octadecadienoic acid (linoleic acid; C18:2); [Z,Z,Z]-9,12,15-octadecatrienoic acid (linolenic acid; C18:3); octadecatetraenoic acid (C18:4); nonadecanoic acid (C19:0); eicosanoic acid (arachidic acid; C20:0); [Z]-9-eicosenoic acid (gadoleic acid; C20:1); eicosadienoic acid (C20:2); eicosatrienoic acid (C20:3); [all-Z]-5,8,11,14-eicosatetraenoic acid (arachidonic acid; C20:4); eicosapentaenoic acid (C20:5); docosanoic acid (behenic acid; C22:0); (Z)-13-docosenoic acid (erucic acid; C22:1); docosadienoic acid (cetoleic acid; C22:2); docosatrienoic acid (C22:3); docosatetraenoic acid (C22:4); docosapentaenoic acid (C22:5); docosahexaenoic acid (C22:6); tetracosanoic acid (lignoceric acid; C24:0); tetracosenoic acid (C24:1); and/or stereoisomers thereof; and/or derivatives thereof, such as for instance hydroxystearic acid; and/or branched chain derivatives thereof, such as for instance isostearic acid.
Derivatives of fatty acids that can be used in embodiments of the invention comprise fatty acids that are substituted with alkyl, aryl, acyl, heteroaryl, halogen, hydroxy or alkoxy.
The term “alkyl”, or “alk” (i.e., derivative forms of alkyl, as in, for instance, “alkoxy”) refers to optionally substituted straight chain or cyclic monovalent alkane (saturated hydrocarbon)-derived radicals containing 1 to 12 carbon atoms. If substituted, alkyl groups may be substituted with up to 4 substituent groups at any available binding position. Examples of alkyl groups comprise, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, pentyl, hexyl, isohexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl and the like. The alkyl may be optionally substituted with one or more halogens.
The term “aryl”, or derivative forms thereof, refers to monocyclic or bicyclic aromatic rings, e.g., phenyl, substituted phenyl and the like, as well as groups which have fused, e.g. naphthyl, phenanthrenyl and the like, containing from 6 to 30 carbon atoms. Accordingly, an aryl group can contain at least one ring with 6 atoms, while up to 5 of such rings can be present, having therein 22 or 30 atoms, depending on optionally alternating (resonating) double bonds between carbon atoms or suitable hetero atoms. Examples of aryl groups comprise, but are not limited to, phenyl, naphthyl, anthryl, biphenyl and the like.
The term “acyl” refers to the radical RCO−, alone or in combination, for instance with oxygen, nitrogen, sulfur, etc.
The term “heteroaryl” refers to a monocyclic aromatic hydrocarbon group having 5 or 6 ring atoms, or a bicyclic aromatic group having 8 to 10 atoms, containing at least one hetero atom, O, S or N, in which a carbon or nitrogen atom is the point of attachment, and in which one or two additional carbon atoms are optionally substituted by a hetero atom selected from O or S, and in which from 1 to 3 additional carbon atoms are optionally replaced by nitrogen hetero atoms, the heteroaryl group mentioned being optionally substituted as described herein. Examples of heteroaryl groups comprise, but are not limited to, thienyl, furyl, pyrrolyl, pyridinyl, imidazolyl, pyrrolidinyl, piperidinyl, thiazolyl, oxazolyl, triazolyl, pyrazolyl, isoxazolyl, isothiazolyl, pyrazinyl, pyridazinyl, pyrimidinal, triazinylazepinyl, indolyl, isoindolyl, quinolinyl, isoquinolinyl, benzothiazolyl, benzoxazolyl, benzimidazolyl, benzoxadiazolyl, benzofurazanyl, etc. The heteroaryl groups can be optionally substituted by one or more groups which comprise, but which are not limited to, halogen, alkyl, alkoxy, hydroxy, carboxy, carbamoyl, alkyloxycarbonyl, trifluoromethyl, cycloalkyl, nitro, cyano, amino, alkyl-S(O)m (wherein m=0, 1 or 2), thiol and the like.
The term “halogen” or “halo” refers to chlorine, bromine, fluorine or iodine, the preferred halogen being bromine.
Preferably, the fatty acid in the metal salt of a fatty acid is selected from the group consisting of C8-C24 fatty acids, more preferably from the group consisting of C14-C22 fatty acids. Still more preferably, unbranched, naturally occurring fatty acids having between 14 and 22 carbon atoms are used. Particularly preferred are the C16-C20 fatty acids which can be obtained from tallow, the most preferred fatty acid being stearic acid.
The metal salt of a fatty acid can be obtained in any known manner. Thus, for instance, very suitably, an oil or fat as a source of a fatty acid can be saponified with a metal hydroxide, whereby the ester bonds are hydrolyzed and the fatty acids are split off from the glycerol backbone. The skilled person is familiar with the methods that can be used for that purpose. Thus, for instance, a metal salt of a fatty acid can be prepared from tallow, an animal fat having a melting point above 40° C. which consists substantially of completely esterified fatty acid-glycerol esters, by saponifying the tallow in water with an alkaline solution of a metal hydroxide, optionally followed by salting out the excess alkali and separating the soap from the glycerol to obtain the metal salt of a fatty acid. In this way, mixtures of fatty acid salts are obtained, which can also find application in embodiments of the invention. Mixtures of fatty acid salts where, as metal of the metal salt, sodium or potassium is used are generally called soap.
Suitable metal salts of a fatty acid are also commercially available, inter alia from Peter Greven Fett-Chemie, Münstereifel, Germany and from AKM, forming part of Safic Alcom, Malford Court, Hardwick Grange, Warrington, United Kingdom.
The metal salt of a fatty acid can in principle be used in any form, but is preferably used in the form of a powder.
The most preferred metal salt of a fatty acid that is used in aspects of the present invention is zinc stearate (octadecanoic acid) also known by the name of talculin Z (CAS No.: 557-05-1), preferably in powder form.
By using a metal salt of a fatty acid which adheres to the cooperating surfaces of the mirror adjustment mechanism, such as, for instance, an organophilic substance when plastic surfaces are used, what is achieved is that molecules situated close to one of the cooperating surfaces are relatively difficult to displace relative to that surface. This enhances the occurring friction at high frequencies, so that absorption improves as well. Moreover, once applied, the substance remains better present at the desired location, viz. the cooperating surfaces.
Preferably, the metal salt is hydrophobic, so that the mirror adjustment mechanism continues to function in case of frost as well, while preventing rust on metal parts near the mechanism.
Advantageously, the substance can be applied in powder form on at least one of the cooperating surfaces. The substance is preferably applied directly onto the surfaces, for instance by spraying or by atomization. It is also possible, however, to apply the substance onto neighboring parts of the mirror adjustment mechanism. In some way or other, amounts of such applied substance can subsequently end up on the above-mentioned surfaces as well, for instance through shifting or atomization.
The invention further relates to a method for assembling a mirror adjustment mechanism.
The invention also relates to the use of a metal salt of a fatty acid.
Further advantageous embodiments of the invention are embodied by the claims.
The figures are only schematic representations of embodiments of the invention. In the figures, the same or corresponding parts are indicated by the same reference numerals.